I see no one has reponded and this is kinda an old post but ill try and help you, the parallel reistor is not for the headphones it is merely to to provide the speaker amp with a resistive load and the series resistor is to atentuate the output power to something the headphones can use. so the parallel resistor can be anything as long as it is higher than the output impedance of your amp so standard would be 8ohms, so anything higher can work also but what should be noted is that the higher the resistance of the parallel resistor the harder you push your amp also the resistor should be of high wattage disapation so i tend to use 20w non inductive, small wattage resistors can blow under load. the series resitor doesnt really matter it is just so you dont blow up your ears from how powerfull your amp is so anything will work depending on how load you want it to get, the wattage dissapation doesnt matter much either.

Is this necessary to use? I feel like there are an awful lot of people just hooking directly into speaker taps with HE-6s and other orthos. Are there any kinds of amps that this would be more important to use?

Also, can someone point me to some references that would help me calculate the types of resistors I would need to make my own?

Is this necessary to use? I feel like there are an awful lot of people just hooking directly into speaker taps with HE-6s and other orthos. Are there any kinds of amps that this would be more important to use?

Also, can someone point me to some references that would help me calculate the types of resistors I would need to make my own?

Thanks!

nah, you dont require one of these but it is technically safer to use one. Cause it provides a constant load to the amp so the output trannies dont short (if your using ss no need to worry)and also attenuates the output volume with drop resistors so the amp dosnt blow your ears out at like 1/8 of a turn on your volume knob.

If I were to try using a T-amp that puts out around 10W into 8ohms. What would be good values of resistors to use for a 50ohm Hifiman?

The saftey aspect is really only usefull if you are running a tube amp cause the tube amp has output transformers that when running without a load can short across but if you are using a solid state amp you need not worry. Now to find what good resistor values, you need to know what kind of headphones you are using and its efficency basically how loud in db per watt or with headphones miliwatt voltage ect. cause diffrent headphones with diffrent efficentcy will operate at diffrent volumes with the same ammount of power. read the link that kozmo posted with http://sound.westhost.com/project100.htm that will show you a diffrent type of convertetr than the one used in the hifiman adapter but they both do the same thing, and also the article tells you which resistors to use with what amp and ect. All in all the hifiman adapter is extreamly overpriced as the parts in it are only around 10 bucks total at the most and that is if you are using much higher quality resistor that hifiman uses (the ones they use are like 5 bucks for all 4) and the metal box isnt all that nice either.

So, if I have some Cardas non-Pb eutectic solder, and I want to use the HE-adapter only with the HE-6 on a tube amp with 4wpc on an 8ohm tap, which resistors should I use? Mills and Shinkoh? Dueland? Audio Note?

it best to match 8 ohms for an 8 ohm speaker tap? So how about simply removing the series 25R 1/4w piece? then the total is 8.3R instead of 8.8, and there's nothing extra in the signal path.

So, if I have some Cardas non-Pb eutectic solder, and I want to use the HE-adapter only with the HE-6 on a tube amp with 4wpc on an 8ohm tap, which resistors should I use? Mills and Shinkoh? Dueland? Audio Note?

it best to match 8 ohms for an 8 ohm speaker tap? So how about simply removing the series 25R 1/4w piece? then the total is 8.3R instead of 8.8, and there's nothing extra in the signal path.

solder dosnt matter, if you have a tube amp your gonna want some nice allen bradley carbon resistors (the audio not tantalums are good also) no ww or metal film for the ones in series.

for the 2 in parallel somthing above 8 ohms is better (matching dosnt matter this is all off of the 8ohm tap of your amp) i use 10 to 16 ohm resistors in parallel but they should be of high w disapation i use 20w resistors, the ones in series dont matter as much for w dissapation id say above 1/2 w is fine.

so in all together for you amp id use 10 or 16 ohm resistors 20w in parallel, then for the ones in parallel depending on the gain of your amp and how much surface noise there is maybe around 36ohms or 56ohms or 100ohms depending how much hum and other noise are in the amp by itself the higher value the quiter everthing any of these should be atleast 1/2w.(most speaker amps have a bit of hum just due to the fact they wernt designed for headphone use and you dont hear the hum on speakers)

your idea of less things in the signal path wont help you much if you wanted the least stuff in your signal path just run your headphone straight into the taps of your amp, this adapter isnt required it just adjusts many of the things so its more suitable for headphone use.

for example i made one of these for my 2a3/45 tube amp i used 16ohm 20w resistors in parallel and in series i used 100ohm resistors. sounds amazing from my hifimans and my lcd-3.

I'd seen that project100 link before as I was thinking of building one for my 600 ohm Beyers but I wasn't sure if the 120ohm parallel resistor was the way to go. I know that nominally headphone outs are 120ohm, but I thought that typically modern amps were much lower and wasn't sure whether to go for a 10 to 20 ohm resistor instead.

I'm a owner of he500 headphones and ussually I'm listening them directly from outputs of my audiolab 8200cdq (using headphone output or xlr outputs). Lately I borrowed HiFiMan's HE-Adapter to connect my headphones to my Rotel RB1080 200wpch/8Ohm solid state power amplifier. Sonud was generally better. I want to build cables with resistors and bananas but I'm wondering if I could try to connect my hps directly to my amplifier without damaging my equipment. My 8200cdq preamp has -80 to +12 volume control and with the HE-Adapter I was listening at -28 level without any distortion or hum. Has anyone tryed feeding he500 directly from 200W speaker amp?